Use the trigonometric function values of the quadrant angles

Use the trigonometric function values of the quadrant angles to evaluate 7 cos 270 degree + 4 sin 90 degree 7 cos 270 degree + 4 sin 90 degree = (Simplify your answer. Type an integer or a fraction) Use the trigonometric function values of the quadrant angles to evaluate tan 180 degree - 4 sec 0 degree tan 180 degree - 4 sec 0 degree = (Simplify your answer. Type an integer or a fraction) Use the trigonometric function values of the quadrant angles to evaluate the given expression. sin^2 90 degree + 7 cos^2 270 degree + 3 sec 0 degree sin^2 90 degree + 7 cos^2 270 degree + 3 sec 0 degree = (Simplify your answer. including any radicals. Use integers or fractions for any numbers in the expression.) cos^2(0 degree) - sin^2 (-90 degree) cos^2 (0) - sin^2(-90 degree) = (Simplify your answer, including any radicals. Use integers or fractions for any numbers in the expression.)

Solution

15) 7cos270 + 9sin90

we know sin90 = 1;

cos270 = cos(180 +90) = 0

So, 7cos270 + 9sin90 = 9

16) tan180 - 4sec0

tan180 =0; sec0 = 1/cos0 = 1

So, tan180 - 4sec0 = -4

17) sin^2(270) +cos^2(-90)

cos(-90) = cos90 = 0

sin270 = sin(180 +90) = -sin90 = -1

So,sin^2(270) +cos^2(-90)= (-1)^2 =1

18) sin^2(90)+ 7cos^2(270) + 3sec0

= 1 +7(0) +3*1

= 4

19) cos^2(0) - sin^2(-90)

= 1 - 1

=